1. Field of the Invention
The present invention relates to an image sensing device and a distance measuring device/focus detecting device using the image sensing device, and further relates to an image sensing device and a distance measuring device using the image sensing device suitable as, for example, a finder for a movie camera, camera using silver halide film, still video camera, and a distance measuring device installed in an automobile.
2. Description of the Related Art
Conventionally, distance measuring device such as, for example, a non-TTL passive-type distance measuring device 1 comprises an optical unit 4 including a pair of optical systems, and a sensor unit 2 including a pair of sensor arrays S1 and S2, as shown in the perspective view of FIG. 15(a) and the see-through perspective from the optical system of FIG. 15(b). The line connecting the optical axes L1 and L2 of the pair of optical systems is referred to as the optical base length R0, and the line connecting the centers of the pair of sensor arrays S1 and S2 is referred to as the sensor base length R1.
When the optical base length R0 and the sensor base length R1 are parallel, there is no change in the distance X0 (hereinafter referred to as the “image interval”) between the detection positions of the formed images T1 and T2 of the object (hereinafter referred to as the “object image”) detected by the pair of sensor arrays S1 and S2 as shown in (A)–(C) of FIG. 17, even when there is a change in the angle of the distant object (photographic object image) T relative to the distance measuring device 1 as shown in (a)–(c) of FIG. 17.
When, however, the optical base length R0 and the sensor base length R1 are not parallel and maintained an angle θ (i.e., when the right and left sensor arrays S1 and S2 do not achieve epipolar binding) as shown in FIGS. 16(a) and 16(b), there is a change in the image interval X1–X3 detected by the pair of sensor arrays S1 and S2 due to the angle of the measured object (photographic object) T relative to the distance measuring device 1, as shown in FIG. 18. For this reason when the distance to the object (photographic object) is measured by the triangulation principle based on the image interval of the formed images T1 and T2, the measurement result theoretically differs due to the angle of the object T. That is, errors arise in the measurement result due to the rotation of the object (photographic object) relative to the distance measuring device 1. When such a distance measuring device 1 is used in a camera, it is impossible to take a photograph which is accurately focused on the photographic object.
Since the angle θ formed by the optical base length R0 and the sensor base length R1 cannot be measured until after the distance measuring device 1 is assembled, it is extremely difficult to assemble the device such that the angle θ formed by the two base lengths is 0°.